adding public animation_start event + trivial syntax change on indicators
syntax change
Flickr now uses https - updated URL
Merge pull request #7 from shayc/development

Flickr now uses https - updated URL
fix scroll offset calculation
Added offset field

The field is needed in cases where the user uses the scroll to move and
it is so fast that all the items are removed from the list and we have
to find which to show.
Avoid error if positionedSurfaces is empty
Don't fail if positionedSurfaces is empty
Fix in case movement is beyond boundaries
Push and pop functions with empty detection funcionality. Surface pool fix.

- If in some point there are no positioned surfaces, push or unshift
look for the appropiate ones.
- To better use the surfaces pool, free the unused ones before
pushing/unshifting.
Fix when there is no bottomSurface